flex 透明MenuBar效果的实现

import mx.skins.ProgrammaticSkin;
import flash.display.Graphics;

public class MenuBarNoBorderFillSkin extends ProgrammaticSkin{
public function MenuBarNoBorderFillSkin(){
super();
}
}

import mx.skins.ProgrammaticSkin;

public class MenuBarActiveSkin extends ProgrammaticSkin{
public function MenuBarActiveSkin(){
super();
}
override protected function updateDisplayList(w:Number, h:Number):void{
var backgroundAlpha:Number = getStyle("backgroundAlpha");
var rollOverColor:uint=getStyle("rollOverColor");
graphics.clear();

drawRoundRect(0,0,w,h,5,rollOverColor,backgroundAlpha);
}
}